1. Field of the Invention
The present invention relates to a seat lock apparatus for a seat in which either one of a sitting side cushion and a backrest side cushion is configured as a movable cushion which can move relative to a vehicle main body, the seat lock apparatus being configured to hold the movable cushion to the vehicle main body.
2. Description of the Related Art
In vehicle seats of four-wheeled motor vehicles, there are some vehicle seats which include a sitting side cushion (hereinafter, referred to as a “seat cushion”) and a backrest side cushion (hereinafter, referred to as a “seatback”) and in which the seatback is configured as a movable cushion which can move relative to a vehicle main body. In the seats of this type, when the seatback that is the movable cushion is erected to be held to the vehicle main body, an occupant can sit on the seat cushion, while when the seatback is folded down to move away from the vehicle main body, a further storage space is obtained. Normally, in a seat in which a seat cushion is configured as a movable cushion, a seat lock apparatus is provided on either one of a seatback or the vehicle main body. The seat lock apparatus is configured to hold the seatback in an erected state by restraining a striker which is provided on the other one of the seatback and the vehicle main body when the seatback is erected.
In the seat lock apparatus, there are provided a case member which has a striker entrance groove which the striker enters and a hook lever which is supported rotatably on a hook shaft which is provided on the case member. The hook lever moves between an opening position where the hook lever opens an opening of the striker entrance groove and a restraining position where the hook lever closes the opening of the striker entrance groove. In the seat lock apparatus configured in the way described above, when the seatback is positioned in the erected state, the striker which enters the striker entrance groove is held by the hook lever which is positioned in the restraining position and deepest surface portions of the striker entrance groove which are situated on both sides of the hook lever (for example, refer to Japanese Patent No. 5157023). This prevents the disengagement of the striker from the striker entrance groove, whereby the seatback is held in the erected state, and the seat is held in a sitting state.